SUSTAINABILITY
“Companies and
governments are on
the lookout for ways
to incorporate more
recycled asphalt
into road building
and rehabilitation
projects.”
There are several technologies that enable
RAP reuse in the production of fresh mix,
including counter-flow dryers (100% hot
recycled material); parallel-flow dryers (up to
60% hot recycled material); middle ring dryers
(up to 40% recycled material); and various cold
addition systems (25–40% recycled material).
Kirsten Barnes is a waste economy analyst
at GreenCape — a non-profit organisation
established in 2010 by the Western Cape
Government to support the development
of the ‘green’ economy in the region.
OR Tambo International Airport
A paper presented at the 33rd Southern
African Transport Conference (Makgoka
et al., 2014) examined the use of warmed
asphalt with a recycled asphalt (RA)
content of 55% using a foamed bitumen
process during an Airports Company
South Africa (Acsa) project. At that time,
this was the highest amount of recycled
asphalt ever produced in an asphalt plant
in South Africa.
The project involved the rehabilitation
of the cargo area at OR Tambo
International Airport, and the use of this
According to Barnes, nationally, other than
the requirement to reduce waste to landfill,
which is embedded within the National
Environmental Management: Waste Act,
2008 (Act No. 59 of 2008), there’s no strict
legislative bans or diversion targets related to
C&D waste.
“However,” she adds, “we expect that to
change, because both the City of Cape Town and
the Provincial Department of Environmental
Affairs in the Western Cape have C&D waste as
one of their key focus areas.” n
environmentally sustainable technology
resulted in massive cost savings while
allowing the contractor to work effectively
in a highly congested area using
conventional asphalt paving and milling
equipment.
This approach was based on experience
gained on previous Acsa projects where
various environmentally sustainable
asphalt products had been used effectively,
including foamed treated asphalt with 35%
RA, haul road with only RA with a surface
emulsion treatment, and cold-mixed RA
mixes with emulsion.
Warmed asphalt with a recycled asphalt content of 55% was used during the
rehabilitation of the cargo area at OR Tambo International Airport.
Sources
1.
2.
3.
Makgoka, M., Grobler, J.E., Marais, H. & Bakker, D. 2014. Environmentally sustainable use
of recycled asphalt at OR Tambo International Airport. Paper presented at the 33rd Annual
Southern African Transport Conference 7–10 July 2014 “Leading Transport into the
Future”. CSIR International Convention Centre, Pretoria, South Africa.
https://repository.up.ac.za/handle/2263/45545.
Mhlongo, S.M., Abiola, O.S., Ndambuki, J.M., & Kupolati, W.K. 2014. Use of recycled asphalt
materials for sustainable construction and rehabilitation of roads. Paper presented at the
International Conference on Biological, Civil and Environmental Engineering (BCEE-
2014), 17–18 March 2014. Dubai, UAE. http://iicbe.org/upload/8428C0314157.pdf.
Ulubeyli, S., Kazaz, A. & Arslan, V. 2017. Construction and demolition waste recycling
plants revisited: Management issues. Procedia Engineering, 172:1190-1197.
QUARRY SA | NOVEMBER 2017 _ 29